Tilth and Tillage
Soil is the medium in which crops are grown but in its natural state, it is not in an ideal condition to grow them satisfactorily. Surface soil in which seed are to be sown, should not be hard & compact, but soft & friable, so that tender shoots of germinating seeds can push above the soil surface without any difficulty and the young roots penetrate easily into the lower layers of soil in search of food, water & air, Soil should also be free from weeds which otherwise rob the crop of water & nutrients. It should also have sufficient water & air which are very necessary for plant growth.
Such ideal condition of soil can be achieved by manipulating the soil properly & bringing it in good filth through a series of mechanical operations like ploughing, clod crushing, dicing, harrowing, leveling, compacting, interculturing etc. by tillage implements.
Tillage: Tillage is as old as Agriculture, Primitive man used to disturb the soil for placing seed Jethro Till considered as ‘Father of Tillage’ Who Written’ Horse hocing Husbandry’ book. Tillage of the soil consists of breaking the hard compact surface to a certain depth and other operations that are followed for plant growth. Tillage is the physical manipulation of soil with tools & the tilling of land for the cultivation of crop plants i.e. the working of the surface soil for bringing about conditions favorable for Raising of crop plants. Tillage is the manipulation of soil with tools & implements for loosening the surface crust & bringing about conditions favorable for the germination of seeds and the growth of crops.
Soil Tilth: Soil Tilth is the term used to express soil condition resulting from tillage. Hence it is the resultant of the tillage. A soil is said to be in good Tilth when it is soft, friable & properly aerated. The Tilth is the physical condition of the soil brought out by tillage that influences crop emergence, establishment, growth and development. Tilth is a loose, friable, airy, powdery granular & crumbly structure of the soil with optimum moisture content suitable for working & germination or sprouting seeds & propagates Soil Tilth is that kind of physical condition of soil when it is loose. Not very powdery but granular & when these granules are felt between fingers they are soft, friable, & crumble easily under pressure, Such soils permit easy infiltration of water & are retentive of moisture for satisfactory growth of plants.
Characteristics of good tilth/Measurement of soil tilth: Tilth indicates two properties of soil, viz the size distribution of aggregates and mellowness or friability of soil.
Size distribution of soil aggregates: The relative proportion of different sized soil aggregates is known as size distribution of soil aggregates. Higher% of larger aggregates i.e. more than 5 mm are necessary for irrigated agriculture while higher% of smaller aggregates(1-2mm) are desirable for dry land agriculture. Theoretically, the best size of granules or aggregates ranges from 1 to 6 mm. However, it depends on soil, type, soil moisture content (at which ploughing is done) & subsequent cultivation.
Mellowness or friability: is that property of soil by which the clods when dry become more crumbly. They do not crumble into dust but remain as stable aggregates of smaller size.
A soil with good tilth is quite porous and has fee drainage up to water table. The capillary & non-capillary pores should be in equal proportion so that sufficient amount of water is retained in the soil as well as free air, The soil aggregates would be quite from or stable & would not be easily eroded by water or by wind.
Soil tilth: is easy to describe but rather difficult to measure/ Theoretically, best size of granules ranges from 1-6 mm differs with country e.g. England as more than 15mm and Russia 2-3 mm. Besides this, study of pore space, equal distribution of macro & micro pores is good tilth.
Ideal soil tilth : An ideal soil tilth is not the same for all types of crops & all types of soils e.g. small seeded crops like bajara, ragi, lucerne, Sesamum, mustard require a much finer seedbed, Jowar & cotton require a moderately compact & firm seed bed and not cloddy or loose. Bold seeded crops like gram, maize germinate even in cloddy seedbed.
As regards soil type, a very fine, powdery condition of the surface soil is decidedly bad for a heavy clay soil as it forms a caked surface under rainy condition and all the rain water is then liable to be lost by run-off, taking away also with loamy & lighter soils.